A variety of means are known and used for tapping a portion of light from a beam of light. Tapping light from a beam is often performed for monitoring purposes; for example a tap signal may be monitored to acquire information with regard to its presence, its amplitude, its wavelength, or some other characteristic of the beam of light. One of the more common taps is in the form of a splitter filter which passes a substantial portion of an incident beam of light to an output port on an output side of the device, and reflects a smaller predetermined portion of the beam to a port on the input side. Although this type of tap adequately performs its intended function, in certain instances there are circuit configurations wherein such taps are less than adequate due to their location within the circuit. For example, most conventional taps are generally well suited to receiving a reflected tap beam adjacent an input port where light is launched; thus in such an instance the tap signal provides information related to the input beam or signal. However, if the beam of light launched into several optical components is modified by those components in some manner, as is often the case, a tap at the input of the optical circuit would not contain information related to the condition or state of the light at or near the output of the circuit.
It is therefore an object of this invention, to provide a circuit having a tap at or near the output.
It is a further object of this invention, to provide a arrangement of optical components that provides forward tapping at the output end of a device.
It is a further object of the invention to provide a coupler for coupling light from at least two output ports on a same end face of a lens, to a single port at another lens.